The present invention relates to an intake device for internal combustion engines. More specifically, the present invention relates to an intake device for internal combustion engines that allows the lengths of branching paths to be uniform, thereby improving output performance of the internal combustion engine. Additionally, the present invention relates to an intake device for internal combustion engines having smooth branching paths, thereby reducing intake resistance. The present invention relates to an intake device for internal combustion engines having a more compact and lightweight intake manifold, thereby reducing fuel consumption and improving power performance. Finally, the present invention relates to an intake device for internal combustion engines having a more compact internal combustion engine, thereby improving ease of mounting in an automobile and making the automobile lighter.
In conventional internal combustion engines mounted in cars, an intake device is disposed to guide intake gas into a plurality of gas columns. In this conventional intake device, there is an intake manifold that guides the intake gas to the gas columns. A throttle body adjusts the air intake.
Referring to FIG. 16, an internal combustion engine 202, mounted in an automobile (not shown), includes a cylinder block 204 having an oil pan 210. A cylinder head 206 is covered by a head cover 208. In this conventional internal combustion engine 202, a plurality of gas columns, e.g., four gas columns numbers 1-4 (not shown in the figure), are arranged in a row. An intake device 212 is positioned at cylinder head 206.
Air intake device 212 includes a throttle body 214 and an intake manifold 216. Throttle body 214 adjusts air intake using an internal throttle valve (not shown in the figure). Intake manifold 216 guides intake gas to the gas columns.
Referring to FIG. 17, an attachment flange 218 attaches to cylinder head 206. First through fourth branching pipes 220-1-220-4 correspond to the first through fourth gas columns numbers 1-4. A surge tank 222 restricts intake gas ripples.
Surge tank 222 is positioned at a gas column row center C along a gas column row direction D formed by the four gas columns numbers 1-4 of internal combustion engine 202. The ends of first through fourth branching pipes 220-1-220-4 connect to attachment flange 218. The other ends of first through fourth branching pipes 220-1-220-4 connect to surge tank 222.
With this conventional intake manifold 216, first and second branching pipes 220-1 and 220-2 connect to attachment flange 218 on one side of gas column center C along gas column row direction D. The other end of first and second branching pipes 220-1 and 220-2 connect to a side wall 224 of surge tank 222 facing one side of gas column direction D. Also, in intake manifold 216, third and fourth branching pipes 220-1 and 220-2 connect to attachment flange 218 on the other side of gas column center C along gas column row direction D. The other end of third and fourth branching pipes 220-3 and 220-4 connect to an opposite side wall 226 of surge tank 222, facing the other side of gas column direction D.
Thus, with conventional intake manifold 216, first through fourth branching pipes 220-1-220-4 are disposed symmetrically around gas column row center C, connecting attachment flange 218 with surge tank 222. This allows first through fourth branching paths 228-1-228-4 to have uniform lengths.
This type of intake device for internal combustion engine is disclosed in Japanese laid- open patent publication number 5-180091, Japanese utility model publication number 2549543, and Japanese laid-open utility model publication number 5-21161.
In the disclosure in Japanese laid-open patent publication number 5-180091, the branching pipes are all grouped together and connected lengthwise to the surge tank. A contact section is disposed where the intake manifold attachment flange abuts the main engine unit. A chamber is disposed below the intake path of the contact section. A partitioning wall is disposed to partition the chamber into upper and lower divisions, and a communicating section is disposed to connect the two divisions. Communicating paths are disposed to connect the intake paths of each of the gas columns to one of the divisions, and an EGR path is disposed to send exhaust gas to the other chamber.
Referring to FIG. 15, the disclosure in Japanese utility model publication number 2549543 is roughly similar to what is shown in the figure. The path width of the curving intake pipes connected to the surge tank are roughly uniform. The cross-sections thereof are formed so that the curvature at the outside of the curve is greater than the curvature at the inside of the curve.
The cross-section shapes of the curving branches of the intake manifold are formed as ellipses so that their centroids are positioned closer toward the outside of the curves rather than at the centers of the intake pipes.
However, with the conventional intake devices of internal combustion engines, there are cases when the surge tank cannot be disposed at the center of the gas column row due to restrictions imposed by how the internal combustion engine is mounted in the automobile and the like.
Referring to FIG. 18, for example, in intake manifold 216 of intake device 212 a center C1 of surge tank 222 is offset by a distance M toward a third gas column #3 toward one side of gas column row direction D.
With manifold 216 having surge tank 222 offset in this manner, first through fourth branching pipes 220-1 through 220-4 are disposed so that the path lengths of first and second branching paths 228-1 and 228-2 of first and second branching pipes 220-1 and 220-2 are longer than the path lengths of third and fourth branching paths 228-3 and 228-4 of third and fourth branching pipes 220-3 and 220-4.
Thus, with this conventional intake device 212, the path lengths of first through fourth branching paths 228-1 through 228-4 cannot be made uniform. The non-uniformity results in variations in intake air flow through first through fourth gas columns #1 through #4. This reduces the output performance of internal combustion engine 202.
The path lengths of first through fourth branching paths 228-1 through 228-4 can be made uniform by having first and second branching pipes 220-1 and 220-2 formed with a larger curvature, resulting in a tighter curve, compared to third and fourth branching pipes 220-3 and 220-4.
Referring to FIGS. 19 and 20, compared to branching pipe 220, as shown in FIG. 19, formed with a small curvature resulting in a more gradual curve, branching pipe 220, as shown in FIG. 20, is formed with a larger curvature, resulting in a tighter curve. This leads to increased intake resistance due to the tighter curve in branching path 228. Thus, the output performance of the internal combustion engine is reduced.
It is an object of the present invention to provide an intake device for an internal combustion engine which overcome the foregoing problems
It is a further object of the present invention to provide an intake device for an internal combustion engine which allows the length of the branching paths to be uniform, thereby improving output performance.
It is another object of the present invention to provide an intake device for an internal combustion engine which has smooth branching parts, thereby reducing intake resistance.
It is yet a further object of the present invention to provide an intake device for an internal combustion engine which has a more compact and lightweight design, thereby reducing fuel consumption, improving power performance, improving the ease of mounting in an automobile, and making the automobile lighter.
Briefly stated, the present invention provides a branching pipes connecting a surge tank to an intake manifold of an internal combustion engine. The branching pipes are made such that each gas column of the internal combustion receives a uniform intake volume. This is achieved by either making each branching pipe of the same length, or by adjusting the inside diameters of the branching pipes, thereby creating a flow delay of the intake into the gas columns, resulting in uniform intake volume. The inside diameters of the branching pipes are either made uniformly of a different diameter, or, alternatively, the inside diameters of the branching pipes include throttles for reducing the diameter of the branching pipe at a localized portion. In both cases, a flow delay of the intake into the gas columns is compensated, resulting in a uniform intake volume. The branching pipes of the present invention result in an improved output performance for the internal combustion engine; provide for smooth branching paths; reduce intake resistance; allow the intake manifold to be made compact and light; reduce fuel consumption; improve power performance; allow the internal combustion engine to be made compact; allow easier mounting in automobiles; and allow automobiles to be lighter.
According to an embodiment of the present invention, there is provided an intake device for an internal combustion engine comprising: attachment means for attaching the intake device to an intake manifold having at least first and second gas columns on the internal combustion engine; at least first and second branching pipes, each connecting one of the at least first and second gas columns to a surge tank; the surge tank having a center positioned a prescribed distance from a center of the at least first and second gas columns; and the at least first and second branching pipes connecting to the surge tank such that first and second branching pipes, corresponding to first and second gas columns having consecutive intake timings, connect, facing each other, at opposite sides of the surge tank.
According to a feature of the present invention, there is provided an intake device for an internal combustion engine comprising: attachment means for attaching the intake device to an intake manifold, having at least first and second gas columns, on the internal combustion engine; at least first and second branching pipes, each connecting one of the at least first and second gas columns to a surge tank; the surge tank having a center positioned a prescribed distance from a center of the at least first and second gas columns; the at least first and second branching pipes having a corresponding at least first and second inside diameters; the first branching pipe, having a shorter path length than the second branching pipe, has a larger diameter than a diameter of the second branching pipe, whereby a flow delay of the intake into the at least first and second gas columns is compensated, resulting in a uniform intake volume; and the at least first and second branching pipes connecting to the surge tank such that first and second branching pipes, corresponding to first and second gas columns having consecutive intake timings, connect, facing each other, at opposite sides of the surge tank.
According to a further feature of the present invention, there is provided an intake device for an internal combustion engine comprising: attachment means for attaching the intake device to an intake manifold having at least first and second gas columns on the internal combustion engine; at least first and second branching pipes, each connecting one of the at least first and second gas columns to a surge tank; the surge tank having a center positioned a prescribed distance from a center of the at least first and second gas columns; the first branching pipe, having a longer path length than the second branching pipe, has a throttle projecting from an inside wall of the first branching pipe, whereby a flow delay of the intake into the at least first and second gas columns is compensated, resulting in a uniform intake volume; and the at least first and second branching pipes connecting to the surge tank such that first and second branching pipes, corresponding to first and second gas columns having consecutive intake timings, connect, facing each other, at opposite sides of the surge tank.
In the present invention, there is an intake manifold that includes an attachment flange attached to an internal combustion engine. A plurality of branching pipes, corresponding to a plurality of gas columns, are arranged in a row on the internal combustion engine. A surge tank restricts intake gas rippling. The gas columns are attached to side walls of the surge tank, which are perpendicular to a gas column row direction, so that the branching pipes corresponding to gas columns having consecutive intake timings are connected facing each other along the gas column row direction.
In each of the plurality of branching pipes, one end is connected to the attachment flange to form a row along the gas column row direction. The other ends of the branching pipes, connected to the attachment flange to one side of a gas column row center of the plurality of gas columns, and other ends of branching pipes, connected to the attachment flange to another side of the gas column row center, are connected to side walls of the surge tank, perpendicular to the gas column row direction, so that the pipes face each other in an asymmetrical manner along the gas column row direction. The plurality of branching pipes is formed so that branching paths are uniformly long. The plurality of branching pipes is preferably formed from a plate material shaped in the form of pipes with a gradual curve having a small curvature. One end of the plurality of branching pipes is connected to the attachment flange. The other end is connected to the surge tank, which is offset to either side of a gas column row center of the plurality of gas columns along the gas column row direction.
In the intake device for internal combustion engines according to the present invention, the surge tank has side walls that face perpendicular to the gas column row direction. Branching pipes, corresponding to the gas columns having sequential intake timings, are connected to these side walls so that they face each other along the gas column row direction. The other ends of the branching pipes, connected to the attachment flange at one side of the gas column row center along the gas column row direction and the other ends of the branching pipes connected to the attachment flange at the other side of the gas column row center along the gas column row direction, are connected to the side walls of the surge tank so that they face each other and are asymmetrical. The branching paths are preferably formed to have uniform lengths, being preferably formed of plate materials in the shape of pipes. The pipes are formed with gradual curves having small curvatures. One end of each of the pipes is connected to the attachment flange, and the other end is connected to the surge tank, which is offset along the gas column row direction to one side or the other of the gas column center of the plurality of gas columns.
With this intake device, the branching pipes are formed from plate materials that is easily shaped. This allows the branching pipes to be formed so that the branching paths have uniform lengths. As a result, the branching paths are easily formed with uniform lengths, even if the surge tank is offset along the gas column row direction. The branching pipes, which are formed so that the branching paths have uniform lengths, are connected facing each other so that they are asymmetrical along the gas column row direction. Branching pipes corresponding to gas columns that have consecutive intake timings are connected facing each other along the gas column row direction. This allows the branching pipes, whose branching paths have uniform lengths, to be formed having large curvatures without having tight curves. As a result, the projection of the branching pipes in the gas column row direction is kept small while the shapes of the branching paths are made smooth.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.